DLL Files in the System32 Folder

Have you ever noticed that, you can manually change the icons of a folder in windows? Have you tried it?
P.S - the image here describes you the way to do it!!

I tried it once, but unfortunately I had gone through the negative side of it!!

One day, I was in my best mood and checking every available option in windows. Suddenly I realized that, we can add our own icon's besides the default icon, by changing the SHELL32.dll file (it's the default icon's pack). I thought for a while and came up with a great idea (that's what I thought at that moment).
What happens if I replace that dll file?
As I was unable to control my eagerness, I quickly moved that dll file from system32 folder to desktop and restarted my system.

At that moment, I expected this!!

To my surprise, there was nothing on my boot screen!! just that blue background appeared. That is the moment when I understood that, even windows can troll us!! (but this is a huge one).

There is no way to get out of this situation, unless your system is dual boot-able. I installed win7 again with all the drivers, to get back to usual state (thanks to my uncle for providing me the rescue discs).

SO, DON'T EVER EVER TOUCH THE DLL FILES IN SYSTEM32, UNLESS YOU WANT TO TEST YOUR LUCK!!!!!